Ink composition, recording medium, ink jet recording method, and printed matter

ABSTRACT

A compound expressed by General Formula 1, whose weight reduction after 1 hour at 60° C. is no more than 1%, is contained in an ink composition and/or a recording medium. This makes it possible to provide an ink composition, a recording medium, printed matter, and an ink jet recording method with which the light resistance of the printed matter is excellent, there is no ink clogging, and a high-quality image with almost no yellowing of the printed matter can be obtained.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an ink composition, a recordingmedium, an ink jet recording method, and printed matter, and moreparticularly relates to an ink composition, a recording medium, an inkjet recording method with which the optical stability (light resistance)of the printed matter is excellent, there is no ink clogging, theyellowing resistance of the printed matter is excellent, and ahigh-quality image can be obtained.

[0003] 2. Description of the Related Art

[0004] Ink jet recording is a printing method in which tiny drops of anink composition are ejected and made to adhere to a recording mediumsuch as paper. A feature of this method is that images of high qualityand resolution can be printed at high speed with a relativelyinexpensive apparatus.

[0005] Various ink compositions have been proposed in the past for usein recording by this ink jet recording method.

[0006] There has been increasing need in recent years for betterweatherproofness (particularly light resistance) of recorded images, andto this end there have been attempts at adding light stabilizers such ashindered amine compounds to ink compositions.

[0007] For instance, Dyes and Pigments 19 (1992, pp. 235-247) discussesthat the photodegradation of a dye can be prevented by adding2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl (a hindered amine-basedlight stabilizer) to an aqueous solution containing this dye. JapaneseLaid-Open Patent Application H11-170686, which was published in a laterissue of the above journal (Dyes and Pigments 19) discloses a techniquefor stabilizing a water-soluble dye by adding a specific compound (theabove-mentioned 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl or aderivative thereof) to a water-based ink jet recording liquid containingthis water-soluble dye. This compound serves to halt the progress of aphoto-oxidation reaction of a colorant and thereby preventphotodegradation by trapping radicals such as R• (alkyl radicals)produced by the optical excitation of carbonyl compounds and the like,or ROO• (peroxide radicals) produced by a reaction between R• and theoxygen in the air. Printed matter produced by ink jet recording usingthis recording liquid has outstanding light resistance.

[0008] However, while the light resistance of a recorded image is indeedimproved by using an ink composition that contains the above-mentionedlight stabilizer, a new problem is encountered in that if the printedmatter is stored in a file equipped with a film containing anantioxidant composed of a specific phenol derivative, or if such a filmis applied to the printed matter, the printed matter will yellow due tothe effect of the light stabilizer.

[0009] The reason for this is believed to be that the specific phenolderivative reacts through the action of the hindered amine compound orother such light stabilizer contained in the ink composition fixed tothe recording medium. BHT (2,6-di-tert-butyl-4-methylphenol) is anexample of this specific phenol derivative.

[0010] Specifically, the above-mentioned phenol derivative contained inthe film is sublimable and therefore migrates from the film to theprinted matter, the action of the light stabilizer in the printed matterbrings about the dimerization and quinonization of the phenolderivative, and the resulting reaction product is the cause of theyellowing of the printed matter. It is believed that this reaction isparticularly pronounced and yellowing especially apt to occur when thelight stabilizer has oxy radicals.

[0011] Even if the compound used as the light stabilizer does not haveany oxy radicals, an oxidation reaction in the course of the printedmatter being stored in the air can generate oxy radicals in the compoundserving as the light stabilizer, so the yellowing reaction stillproceeds, albeit more slowly, and the printed matter still ends upyellowing.

SUMMARY OF THE INVENTION

[0012] It is therefore an object of the present invention to provide anink composition, a recording medium, an ink jet recording method, andprinted matter with which the light resistance of the printed matter isexcellent, there is no ink clogging, and a high-quality image withalmost no yellowing of the printed matter can be obtained.

[0013] As a result of diligent research, the inventors learned thatprinted matter with excellent light resistance, clogging resistance, andyellowing resistance can be obtained by using an ink compositioncomprising a colorant, water, and a compound expressed by the GeneralFormula 1 of claim 1, whose weight reduction after 1 hour at 60° C. isno more than 1 wt %.

[0014] The inventors also learned that printed matter with excellentlight resistance and yellowing resistance can be obtained if therecording medium has a receiving layer, and if this receiving layercontains a compound expressed by the above-mentioned General Formula 1,whose weight reduction after 1 hour at 60° C. is no more than 1 wt %.

[0015] The present invention was conceived on the basis of thisknowledge, and provides an ink composition comprising a colorant, water,and a compound expressed by the above-mentioned General Formula 1, whoseweight reduction after 1 hour at 60° C. is no more than 1 wt %; and alsoprovides a recording medium having a receiving layer containing acompound expressed by the above-mentioned General Formula 1, whoseweight reduction after 1 hour at 60° C. is no more than 1 wt %. Thepresent invention further provides printed matter obtained by using thisink composition and/or this recording medium, and a recording methodusing the same.

[0016] As mentioned above, one of the causes of yellowing of printedmatter is that the phenol derivative in the film sublimates and migratesinto the printed matter, where it reacts with the compound expressed byGeneral Formula 1, which is added as a light stabilizer. The presentinvention was conceived in light of the discovery that another cause ofthe yellowing of printed matter is that the compound expressed byGeneral Formula 1 is also sublimable, and that yellowing of the printedmatter can be prevented by adjusting the proportional evaporation ofthis compound (its weight reduction) to a specific value. The presentinvention is characterized in that the weight reduction of the compoundexpressed by General Formula 1 is set to a specific value, and there areno particular restrictions on the compound expressed by General Formula1 as long as this specific value is attained.

[0017] In the above, it is preferable for the compound expressed byGeneral Formula 1 to have a water-soluble group W (where W is a —SO₂NH₂group, —NHCOCH₃ group, —CONH₂ group, —C═NH(NH₂) group, —NHC═NH(NH₂)group, —SO₃H group, sulfuric ester group, —P(O) (OH) (OR), —P(O) (OR)₂,carbamoyl group or salt thereof, salt of a carboxyl group, salt of anamino group, salt of a phenolic hydroxyl group, polyethylene glycolether group, salt of —C═NH(NH₂), or salt of —NHC═NH(NH₂) (R is an alkylgroup or aryl group)).

[0018] In the above-mentioned compound expressed by General Formula 1,it is preferable for Z to be a group of nonmetal atoms necessary tocomplete a six-member ring.

[0019] The above-mentioned compound expressed by General Formula 1 ispreferably contained in the ink composition in an amount of at least0.05 wt % and no more than 10 wt %.

[0020] The above-mentioned ink composition may further include apenetrant and/or a humectant.

[0021] The above constitution prevents the dimerization andquinonization of the phenol derivative, so the resulting printed matterhas excellent light resistance and excellent yellowing resistance.

[0022] In order to ensure sufficient ink absorption by the recordingmedium and obtain yellowing resistance, it is preferable for thecompound expressed by General Formula 1 to be contained in theabove-mentioned recording medium of the present invention in an amountof at least 0.01 wt % and no more than 10 wt % with respect to the totalweight of the above-mentioned ink receiving layer, with a range of atleast 0.5 wt % and no more than 5 wt % being even better.

[0023] The ink jet recording method of the present invention involvesdischarging droplets of an ink composition and causing these droplets toadhere to a recording medium, and is characterized by the use of theabove-mentioned ink composition as this ink composition.

[0024] Also, the ink jet recording method of the present inventioninvolves discharging droplets of an ink composition and causing thesedroplets to adhere to a recording medium, and is characterized by theuse of the above-mentioned recording medium as this recording medium.

[0025] Using these recording methods makes it possible to obtain printedmatter with excellent light resistance and excellent yellowingresistance.

[0026] Also, as a result of diligent research, the inventors discoveredthat printed matter with excellent light resistance, cloggingresistance, and yellowing resistance can be obtained if the inkcomposition further contains at least one type of a specific compound A.

[0027] The hydrazide compound in the present invention refers tocorresponding carboxylic esters, acid halides, thiocarboxylic acids andother such acid derivatives, or sulfonic acid, chlorosulfonic acid, andother such sulfone derivatives, or a compound having a —CXNHNR⁸R⁹ (whereR⁸ and R⁹ are each a hydrogen, alkyl group, or aryl group, and X is S orO) group or a —SO₂NHNR⁸R⁹ (where R⁸ and R⁹ are each a hydrogen, alkylgroup, or aryl group), obtained by a condensation reaction between anisocyanate or diisocyanate and a hydrazine compound expressed by thegeneral formula NH₂NR⁸R⁹ (where R⁸ and R⁹ are each a hydrogen, alkylgroup, or aryl group).

[0028] The inventors also learned that printed matter with excellentlight resistance and yellowing resistance can be obtained if theabove-mentioned receiving layer further contains at least one type of aspecific compound A.

[0029] The present invention was conceived on the basis of the aboveknowledge, and provides an ink composition comprising a colorant, water,a compound expressed by the following General Formula 1, whose weightreduction after 1 hour at 60° C. is no more than 1%, and at least onetype of compound A selected as desired from among the three groupsnumbered I to III below; and also provides a recording medium having areceiving layer containing a compound expressed by the following GeneralFormula 1, whose weight reduction after 1 hour at 60° C. is no more than1%, and at least one type of compound A selected as desired from amongthe three groups numbered I to III below.

[0030] Group I: hydrazide compounds

[0031] Group II: tertiary amine compounds

[0032] Group III: inorganic salts expressed by MS₂O₄, MSO₃, MS₂O₃,MPH₂O₂, and MPHO₃ (where M is an alkali metal or alkaline earth metal)

[0033] The present invention further provides printed matter obtainedusing this ink composition and/or recording medium, and a recordingmethod.

[0034] One of the causes of yellowing of printed matter is that thephenol derivative in the film sublimates and migrates into the printedmatter, where it reacts with the compound expressed by General Formula1, which is added as a light stabilizer. The present invention wasconceived in light of the discovery that another cause of the yellowingof printed matter is that the compound expressed by General Formula 1 isalso sublimable, and that yellowing of the printed matter can beprevented by adjusting the proportional evaporation of this compound(its weight reduction) to a specific value, and adding a specificadditive. There are no particular restrictions on the compound expressedby General Formula 1 as long as the weight reduction attains thisspecific value.

[0035] In the above, it is preferable for the compound expressed byGeneral Formula 1 to have a water-soluble group W (where W is a —SO₂NH₂group, —NHCOCH₃ group, —CONH₂ group, —C═NH(NH₂) group, —NHC═NH(NH₂)group, —SO₃H group, sulfuric ester group, —P(O) (OH) (OR), —P(O) (OR)₂,carbamoyl group or salt thereof, salt of a carboxyl group, salt of anamino group, salt of a phenolic hydroxyl group, polyethylene glycolether group, salt of —C═NH(NH₂), or salt of —NHC═NH(NH₂) (R is an alkylgroup or aryl group)).

[0036] In the above-mentioned compound expressed by General Formula 1,it is preferable for Z to be a group of nonmetal atoms necessary tocomplete a six-member ring.

[0037] In the above-mentioned compound expressed by General Formula 1, Xmay be an oxy radical.

[0038] In order to obtain sufficient light resistance, cloggingresistance, and yellowing resistance, it is preferable for theabove-mentioned compound A to be contained in the above-mentioned inkcomposition in an amount of at least 0.01 wt % and no more than 10 wt %,with a range of at least 0.5 wt % and no more than 5 wt % being evenbetter.

[0039] In order to obtain sufficient light resistance, cloggingresistance, and yellowing resistance, it is preferable for theabove-mentioned compound expressed by General Formula 1 to be containedin the above-mentioned ink composition in an amount of at least 0.05 wt% and no more than 10 wt % with respect to the total amount of ink, witha range of at least 0.5 wt % and no more than 5 wt % being even better.

[0040] From the standpoint of increasing the yellowing resistance of theprinted matter, it is preferable if the compound expressed by GeneralFormula 1 and compound A are present in a weight ratio (former/latter)of at least 1:25 and no more than 5:1, with at least 1:5 and no morethan 3:1 being particularly favorable.

[0041] In the above, the hydrazide compound is preferably a compoundexpressed by the general formula R⁵CXNHNR⁶R⁷ (where R⁵ is an alkyl groupor aryl group; R⁶ and R⁷ are a hydrogen, alkyl group, or aryl group; andX is S or O), or the general formula R⁵SO₂NHNR⁶R⁷ (where R⁵ is an alkylgroup or aryl group; and R⁶ and R⁷ are a hydrogen, alkyl group, or arylgroup), or the general formula R⁵NHCXNHNR⁶R⁷ (where R⁵ is an alkyl groupor aryl group; R⁶ and R⁷ are a hydrogen, alkyl group, or aryl group; andX is S or O).

[0042] The hydrazide compound may have two or more hydrazide structuresper molecule.

[0043] In the above, the tertiary amine compound is preferably acompound expressed by the general formula R⁵R⁶R⁷N (where R⁵, R⁶, and R⁷are each a substitutable alkyl group, aryl group, or aralkyl group), ora substitutable cyclic tertiary amine.

[0044] In the above, the inorganic salt is one or more inorganic saltsselected from the group consisting of compounds expressed by MS₂O₄,MSO₃, MS₂O₃, MPH₂O₂, and MPHO₃ (where M is an alkali metal or alkalineearth metal).

[0045] The inorganic salt is preferably a potassium salt or sodium salt.

[0046] When compound A is selected from group I and used as an additive,it has the effect of giving the printed matter excellent lightresistance, clogging resistance, and yellowing resistance, as well asimproving the gas resistance of the printed matter.

[0047] The above-mentioned ink composition may further comprise apenetrant and/or a humectant.

[0048] The above constitution prevents the dimerization andquinonization of the phenol derivative, so the resulting printed matterhas excellent light resistance and excellent yellowing resistance.

[0049] In order to ensure sufficient ink absorption by the recordingmedium and obtain yellowing resistance, it is preferable for compound Ato be contained in the above-mentioned recording medium of the presentinvention in an amount of at least 0.01 wt % and no more than 10 wt %with respect to the total weight of the above-mentioned ink receivinglayer, with a range of at least 0.5 wt % and no more than 5 wt % beingeven better.

[0050] In order to ensure sufficient ink absorption by the recordingmedium and obtain yellowing resistance, it is preferable for thecompound expressed by General Formula 1 to be contained in theabove-mentioned recording medium of the present invention in an amountof at least 0.01 wt % and no more than 10 wt % with respect to the totalweight of the above-mentioned ink receiving layer, with a range of atleast 0.5 wt % and no more than 5 wt % being even better.

[0051] In order to ensure sufficient ink absorption by the recordingmedium and obtain yellowing resistance, it is preferable if the compoundexpressed by General Formula 1 and compound A are present in a weightratio (former/latter) of at least 1:25 and no more than 5:1, with atleast 1:5 and no more than 3:1 being particularly favorable.

[0052] The ink jet recording method of the present invention involvesdischarging droplets of an ink composition and causing these droplets toadhere to a recording medium, and is characterized by the use of theabove-mentioned ink composition as this ink composition.

[0053] Also, the ink jet recording method of the present inventioninvolves discharging droplets of an ink composition and causing thesedroplets to adhere to a recording medium, and is characterized by theuse of the above-mentioned recording medium as this recording medium.

[0054] The ink jet recording method of the present invention involvesdischarging droplets of an ink composition and causing these droplets toadhere to a recording medium, and is characterized by the use of theabove-mentioned ink composition as this ink composition, and by the useof a recording medium in which an ink receiving layer is provided over asubstrate, and which contains compound A in this ink receiving layer, asthis recording medium.

[0055] The ink jet recording method of the present invention involvesdischarging droplets of an ink composition and causing these droplets toadhere to a recording medium, and is characterized by the use of an inkcomposition containing a colorant, water, and compound A as this inkcomposition, and by the use of the above-mentioned recording medium asthis recording medium.

[0056] Using these recording methods makes it possible to obtain printedmatter with excellent light resistance and excellent yellowingresistance.

[0057] The inventors conducted further research on the basis of theseinventions, and as a result discovered that printed matter withexcellent light resistance, clogging resistance, and yellowingresistance is similarly obtained when the above-mentioned compoundexpressed by General Formula 1, whose weight reduction after 1 hour at60° C. is no more than 1%, is contained in the ink composition, and whenat least one type of a specific compound A is contained in the recordingmedium.

[0058] Specifically, the ink jet recording method of the presentinvention is characterized in that the ink composition comprises acolorant, water, and a compound expressed by the following GeneralFormula 1, whose weight reduction after 1 hour at 60° C. is no more than1%, and the recording medium contains at least one type of compound Aselected as desired from among the three groups numbered I to III above.

[0059] The ink jet recording method of the present invention involvesdischarging droplets of an ink composition and causing these droplets toadhere to a recording medium, and is characterized by the use of an inkcomposition containing a colorant, water, and the above-mentionedcompound expressed by the following General Formula 1, whose weightreduction after 1 hour at 60° C. is no more than 1%, as this inkcomposition, and by the use of the above-mentioned recording medium asthis recording medium.

[0060] In order to ensure sufficient ink absorption by the recordingmedium and obtain yellowing resistance in the above-mentioned recordingmethod of the present invention, it is preferable for compound A to becontained in an amount of at least 0.01 wt % and no more than 10 wt %with respect to the total weight of the above-mentioned ink receivinglayer, with a range of at least 0.5 wt % and no more than 5 wt % beingeven better.

[0061] In order to ensure sufficient ink absorption by the recordingmedium and obtain yellowing resistance in the above-mentioned recordingmethod of the present invention, it is preferable the compound expressedby General Formula 1 to be contained in an amount of at least 0.05 wt %and no more than 10 wt % with respect to the total weight of theabove-mentioned ink receiving layer, with a range of at least 0.5 wt %and no more than 5 wt % being even better. It is also preferable for thecompound A content to be at least 0.01 wt % and no more than 10 wt %.

[0062] Using these recording methods makes it possible to obtain printedmatter with excellent light resistance and excellent yellowingresistance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Ink Composition

[0063] Preferred embodiments of the ink composition of the presentinvention will now be described.

[0064] The ink composition pertaining to the present invention ischaracterized by comprising a colorant, water, and a compound expressedby the above-mentioned General Formula 1, wherein the weight reductionin the compound expressed by said General Formula 1 after 1 hour at 60°C. is no more than 1%.

[0065] (In General Formula 1, X is a hydrogen, oxy radical, hydroxylgroup, alkyl group, alkenyl group, alkynyl group, aryl group, acylgroup, sulfonyl group, sulfinyl group, alkoxy group, aryloxy group, oracyloxy group; R¹, R², R³, and R⁴ are each a hydrogen or alkyl group; Zis a group of nonmetal atoms necessary to complete a five- toseven-member ring; and any two groups out of R¹ to R⁴ and Z may bondtogether to form a five- to seven-member ring.)

[0066] The compound expressed by General Formula 1 is preferably acompound expressed by the following general formula, having awater-soluble group W.

[0067] (Where W is a —SO₂NH₂ group, —NHCOCH₃ group, —CONH₂ group,—C═NH(NH₂) group, —NHC═NH(NH₂) group, —SO₃H group, sulfuric ester group,—P(O) (OH) (OR) , —P(O) (OR)₂, carbamoyl group or salt thereof, salt ofa carboxyl group, salt of an amino group, salt of a phenolic hydroxylgroup, polyethylene glycol ether group, salt of —C═NH(NH₂), or salt of—NHC═NH(NH₂) (R is an alkyl group or aryl group); X is a hydrogen, oxyradical, hydroxyl group, alkyl group, alkenyl group, alkynyl group, arylgroup, acyl group, sulfonyl group, sulfinyl group, alkoxy group, aryloxygroup, or acyloxy group; R¹, R², R³, and R⁴ are each a hydrogen or alkylgroup; Z is a group of nonmetal atoms necessary to complete a five- toseven-member ring; and any two groups out of R¹ to R⁴ and Z may bondtogether to form a five- to seven-member ring.)

[0068] Examples of the alkyl group expressed by X in General Formula 1include a methyl group, ethyl group, n-propyl group, iso-propyl group,n-butyl group, tert-butyl group, n-octyl group, benzyl group, andhexadecyl group; examples of the alkenyl group include an aryl group andoleyl group; examples of the alkynyl group include an ethynyl group;examples of the aryl group include a phenyl group and naphthyl group;examples of the acyl group include an acetyl group, benzoyl group, andpentanoyl group; examples of the sulfonyl group include amethanesulfonyl group, benzenesulfonyl group, and toluenesulfonyl group;examples of the sulfinyl group include a methanesulfinyl group andbenzenesulfinyl group; examples of the alkoxy group include a methyloxygroup, ethyloxy group, i-propyloxy group, n-butyloxy group,cyclohexyloxy group, n-octyloxy group, 1-octyloxy group, and benzyloxygroup; examples of the aryloxy group include a phenoxy group; andexamples of the acyloxy group include an acetyloxy group and benzoyloxygroup. All of these groups may have substituents, and examples of suchsubstituents include a sulfonyl group, carboxyl group, and hydroxygroup. It is particularly favorable for X to be an oxy radical.

[0069] As mentioned above, R¹, R², R³, and R⁴ in General Formula 1 areeach a hydrogen or alkyl group. This alkyl group is selected from thesame set as the alkyl group expressed by the above-mentioned X. A methylgroup is particularly favorable.

[0070] It is preferable for Z in the compound expressed by GeneralFormula 1 to be a group of nonmetal atoms necessary to complete asix-member ring.

[0071] Of the compounds expressed by General Formula 1, specificexamples of those whose weight reduction after 1 hour at 60° C. is nomore than 1% will now be given.

[0072] The compound expressed by General Formula 1 can be made by themethods discussed in Journal of Polymer Science, Part B: PolymerPhysics, Vol. 25, 1299-1310 (1987), written by Kunihiro Hamada, ToshiroIijima, and Ralph McGregor, and in Polymer, Vol. 29 (1), 93-98 (1988),written by Kunihiro Hamada, Toshiro Iijima, and Ralph McGregor, forexample. In specific terms, the compound of Formula I-1 can be made bythe first of the methods cited above, while the compound of Formula 1-2can be made by the second of these methods.

[0073] Meanwhile, of the compounds expressed by General Formula 1,specific examples of those whose weight reduction after 1 hour at 60° C.is no more than 1% are expressed by the following.

[0074] In the present invention, the compound expressed by GeneralFormula 1 is preferably contained in the ink composition in an amount ofat least 0.05 wt % and no more than 10 wt %, and more preferably in anamount of at least 0.1 wt % and no more than 5 wt %.

[0075] Also, the ink composition pertaining to the present invention ischaracterized by comprising a colorant, water, a compound expressed bythe following General Formula 1, and the above-mentioned compound A,wherein the weight reduction in the compound expressed by GeneralFormula 1 after 1 hour at 60° C. is no more than 1%.

[0076] Examples of hydrazide compounds include hydrazide (acylhydrazide), thiocarbohydrazide, and derivatives of these.

[0077] More specifically, it is preferable to use a compound expressedby the general formula R⁵CXNHNR⁶R⁷ (where R⁵ is an alkyl group or arylgroup; R⁶ and R⁷ are a hydrogen, alkyl group, or aryl group; and X is Sor O), or the general formula R⁵SO₂NHNR⁶R⁷ (where R⁵ is an alkyl groupor aryl group; and R⁶ and R⁷ are a hydrogen, alkyl group, or arylgroup), or the general formula R⁵NHCXNHNR⁶R⁷ (where R⁵ is an alkyl groupor aryl group; R⁶ and R⁷ are a hydrogen, alkyl group, or aryl group; andX is S or O).

[0078] The yellowing resistance of the printed matter will beparticularly good if the hydrazide compound has two or more hydrazidestructures per molecule.

[0079] The following are specific examples of compounds expressed by thegeneral formula R⁵CXNHNR⁶R⁷, the general formula R⁵SO₂NHNR⁶R⁷, or thegeneral formula R⁵NHCXNHNR⁶R⁷.

[0080] It is preferable for the hydrazide compound to be contained inthe ink composition in an amount of at least 0.01 wt % and no more than10 wt %, with at least 0.1 wt % and no more than 5 wt % beingparticularly favorable. Adjusting to the preferred content markedlyimproves the yellowing resistance of the printed matter.

[0081] In the present invention, it is preferable if the compoundexpressed by General Formula 1 and the hydrazide compound are present ina weight ratio (former/latter) of at least 1:25 and no more than 5:1,with at least 1:5 and no more than 3:1 being particularly favorable.Adjusting to the preferred weight ratio markedly improves the yellowingresistance of the printed matter.

[0082] The tertiary amine compound is preferably a compound expressed bythe general formula R⁵R⁶R⁷N (where R⁵, R⁶, and R⁷ are each asubstitutable alkyl group, aryl group, or aralkyl group), or asubstitutable cyclic tertiary amine.

[0083] The compound expressed by the general formula R⁵R⁶R⁷N may be onein which R⁵, R⁶, and R⁷ are each individually a substitutable alkylgroup, aryl group, or aralkyl group. Specific examples includetriethanolamine, dimethylethanolamine, diethylethanolamine,butyldiethanolamine, methyldiethanolamine, triisopropanolamine,trimethylamine, triethylamine, tripropylamine, tributylamine,triallylamine, dimethylaniline, diethylaniline, tribenzylamine,triphenylamine, N,N-dimethylbenzylamine, N,N-dimethylphenethylamine,N,N-diethylbenzylamine, and derivatives of these. The yellowingresistance of the printed matter will be particularly good when R⁵, R⁶,and R⁷ are all hydroxyalkyl groups.

[0084] Examples of the substitutable cyclic tertiary amine include1,4-diazabicyclo[2.2.2]octane (DABCO),1,8-diazabicyclo[5.4.0]-7-undecene (DBU),1,5-diazabicyclo[4.3.0]-5-nonene (DBN), hexamethylenetetramine (HMTA),N-methylpiperidine, N-methylmorpholine, N-methylpyrrolidine,N-methylpyrrole, 2-methylpyridine, 2-ethylpyridine, 3-methylpyridine,3-methylquinoline, and derivatives of these. The yellowing resistance ofthe printed matter will be particularly good when DABCO or HMTA is used.

[0085] These tertiary amine compounds may be used singly or incombinations.

[0086] The tertiary amine compound is preferably contained in the inkcomposition in an amount of at least 0.01 wt % and no more than 10 wt %,with at least 0.1 wt % and no more than 5 wt % being particularlyfavorable. Adjusting to the preferred content markedly improves theyellowing resistance of the printed matter.

[0087] In the present invention, it is preferable if the compoundexpressed by General Formula 1 and the tertiary amine compound arepresent in a weight ratio (former/latter) of at least 1:25 and no morethan 5:1, with at least 1:5 and no more than 3:1 being particularlyfavorable. Adjusting to the preferred weight ratio markedly improves theyellowing resistance of the printed matter.

[0088] Examples of inorganic salts include one or more types selectedfrom the group consisting of compounds expressed by MS₂O₄, MSO₃, MS₂O₃,MPH₂O₂, and MPHO₃ (where M is an alkali metal or alkaline earth metal).Potassium, sodium, and lithium are favorable as the alkali metal, andmagnesium, calcium, and barium are favorable as the alkaline earthmetal. It is particularly favorable for the inorganic salt of thepresent invention to be a potassium salt or sodium salt.

[0089] Specific examples of inorganic salts include K₂S₂O₄, Na₂S₂O₄,Li₂S₂O₄, MgS₂O₄, CaS₂O₄, BaS₂O₄, K₂SO₃, Na₂SO₃, Li₂SO₃, MgSO₃, CaSO₃,BaSO₃, K₂S₂O₃, Na₂S₂O₃, Li₂S₂O₃, MgS₂O₃, CaS₂O₃, BaS₂O₃, KPH₂O₂,NaPH₂O₂, LiPH₂O₂, Mg(PH₂O₂)₂, Ca(PH₂O₂)₂, Ba(PH₂O₂), K₂PHO₃, Na₂PHO₃,Li₂PHO₃, MgPHO₃, CaPHO₃, and BaPHO₃. The yellowing resistance of theprinted matter will be markedly improved when a potassium salt or sodiumsalt is used.

[0090] These inorganic salts may be used singly or in combinations.

[0091] The inorganic salt is preferably contained in the ink compositionin an amount of at least 0.01 wt % and no more than 10 wt %, with atleast 0.1 wt % and no more than 5 wt % being particularly favorable.Adjusting to the preferred content markedly improves the yellowingresistance of the printed matter.

[0092] In the present invention, it is preferable if the compoundexpressed by General Formula 1 and the inorganic salt are present in aweight ratio (former/latter) of at least 1:25 and no more than 5:1, withat least 1:5 and no more than 3:1 being particularly favorable.Adjusting to the preferred weight ratio markedly improves the yellowingresistance of the printed matter.

[0093] The compound expressed by General Formula 1 is preferably acompound having a water-soluble group W as mentioned above.

[0094] Preferred embodiments, specific examples, and the manufacturingmethod of the compound expressed by General Formula 1 are the same asthose discussed above.

[0095] In the present invention, the compound expressed by GeneralFormula 1 is preferably contained in the ink composition in an amount ofat least 0.05 wt % and no more than 10 wt %, with at least 0.1 wt % andno more than 5 wt % being particularly favorable.

[0096] A dye or pigment can be used as the colorant.

[0097] The dye is preferably water-soluble, specific examples of whichinclude those classified in the Color Index as acid dyes, direct dyes,catalyst dyes, reactive dyes, soluble vat dyes, sulfur dyes, and foodcolorings. Many of those dyes not listed in the Color Index can also beused favorably.

[0098] Specific examples of these include C.I. Direct Black 17, 19, 32,38, 51, 62, 71, 74, 75, 112, 117, 154, 163, and 168, C.I. Acid Black 7,24, 26, 48, 52, 58, 60, 107, 109, 118, 119, 131, 140, 155, 156, and 187,C.I. Food Black 1 and 2, C.I. Reactive Black 5, C.I. Direct Yellow 11,28, 33, 39, 44, 58, 86, 100, 132, 142, and 330, C.I. Acid Yellow 3, 19,23, 25, 29, 38, 49, 59, 62, and 72, C.I. Basic Yellow 11 and 51, C.I.Disperse Yellow 3 and 5, C.I. Reactive Yellow 2, C.I. Direct Red 23, 79,80, 83, 99, 220, 224, and 227, C.I. Acid Red 1, 8, 17, 18, 32, 35, 37,42, 52, 57, 92, 115, 119, 131, 133, 134, 154, 186, 249, 254, and 256,C.I. Basic Red 14 and 39, C.I. Disperse Red 60, C.I. Direct Blue 6, 8,15, 25, 71, 76, 80, 86, 90, 106, 108, 123, 163, 165, 168, 199, and 226,C.I. Acid Blue 9, 29, 40, 62, 74, 102, 104, 113, 117, 120, 175, and 183,C.I. Basic Blue 41, C.I. Reactive Blue 15, C.I. Direct Violet 47, 51,90, and 94, and C.I. Acid Violet 11, 34, and 75.

[0099] There are no particular restrictions on the pigment, which can beeither an inorganic pigment or an organic pigment. Inorganic pigmentsthat can be used include titanium oxide and iron oxide, as well ascarbon black made by a known method such as a contact process, furnaceprocess, or thermal process. The organic pigment can be an azo dye(including azo lake, insoluble azo pigments, condensed azo pigments,chelate azo pigments, and so forth), a polycyclic pigment (such asphthalocyanine pigments, perylene pigments, perinone pigments,anthraquinone pigments, quinacridone pigments, dioxazine pigments,thioindigo pigments, isoindolinone pigments, and quinophthalonepigments), a dye chelate (such as basic dye chelates and acid dyechelates), a nitro pigment, a nitroso pigment, aniline black, or thelike.

[0100] In particular, the carbon black used for black ink can be No.2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100,No. 2200B, or the like from Mitsubishi Chemical, Raven 5750, Raven 5250,Raven 5000, Raven 3500, Raven 1255, Raven 700, or the like fromColombia, Regal 400R, Regal 330R, Regal 1660R, Mogul L, Monarch 700,Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100,Monarch 1300, Monarch 1400, or the like from Cabot, or Color Black FW1,Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200,Color Black S150, Color Black S160, Color Black S170, Printex 35,Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5,Special Black 4A, Special Black 4, or the like from Degussa.

[0101] Examples of pigments used for yellow ink include C.I. PigmentYellow 1, C.I. Pigment Yellow 2, C.I. Pigment Yellow 3, C.I. PigmentYellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14C, C.I. PigmentYellow 16, C.I. Pigment Yellow 17, C.I. Pigment Yellow 73, C.I. PigmentYellow 74, C.I. Pigment Yellow 75, C.I. Pigment Yellow 83, C.I. PigmentYellow 93, C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I. PigmentYellow 98, C.I. Pigment Yellow 119, C.I. Pigment Yellow 110, C.I.Pigment Yellow 114, C.I. Pigment Yellow 128, C.I. Pigment Yellow 129,C.I. Pigment Yellow 138, C.I. Pigment Yellow 150, C.I. Pigment Yellow151, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. PigmentYellow 180, and C.I. Pigment Yellow 185.

[0102] Examples of pigments used for red ink include C.I. Pigment Red 5,C.I. Pigment Red 7, C.I. Pigment Red 12, C.I. Pigment Red 48 (Ca),Pigment Red 48 (Mu), Pigment Red 57 (Ca), C.I. Pigment Red 57:1, C.I.Pigment Red 112, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I.Pigment Red 168, C.I. Pigment Red 184, and C.I. Pigment Red 202.

[0103] Examples of pigments used for blue ink include C.I. Pigment Blue1, C.I. Pigment Blue 2, C.I. Pigment Blue 3, C.I. Pigment Blue 15:3,C.I. Pigment Blue 15:34, C.I. Pigment Blue 15:4, C.I. Pigment Blue 16,C.I. Pigment Blue 22, C.I. Pigment Blue 60, C.I. Vat Blue 4, and C.I.Vat Blue 60.

[0104] The colorant should be added to the ink composition in an amountof at least 0.1 wt % and no more than 20 wt %, with at least 0.5 wt %and no more than 10 wt % being even better. In the case of a pigment,the particle diameter should be no more than 10 μm, and preferably nomore than 0.1 μm.

[0105] Water is used as a solvent in the ink composition of the presentinvention. Ion exchange water, ultrafiltration water, reverse osmosiswater, distilled water, or other such pure water or ultra-pure water canbe used favorably for this water.

[0106] The ink composition of the present invention may also contain apenetrant and/or a humectant.

[0107] The penetrant can be any of a wide range of compounds that lowerthe surface tension of an ink, promote the penetration of the ink intothe recording medium, and shorten the ink drying time. Examples includeethanol, propanol, isopropanol, butanol, pentanol, and other loweralcohols; ethylene glycol monoethyl ether, ethylene glycol monobutylether, and other such cellosolves; diethylene glycol monobutyl ether,triethylene glycol monobutyl ether glycol ether, and other carbitols;and nonionic surfactants.

[0108] The humectant can be any of a wide range of compounds thatsuppress the evaporation of water, keep the ink wet, and improve itsdischarge stability. Examples include ethylene glycol, propylene glycol,diethylene glycol, triethylene glycol, polyethylene glycol,polypropylene glycol, glycerol, diglycerol, 1,3-propanediol,1,5-pentanediol, and other polyhydric alcohols; maltitol, maltose,sorbitol, and other sugars; trimethylolethane, trimethylolpropane, andother glycerol derivatives; ethylene carbonate and other carbonicesters; imidazole, 2-methylimidazole, and other imidazole derivatives;2-pyridinol, 3-pyridinol, and other pyridinol derivatives; and urea.

[0109] If needed, the ink composition of the present invention canfurther contain any auxiliaries commonly used in ink jet recording inks.Examples of such auxiliaries include pH regulators, chelating agents,preservatives, and rust inhibitors.

[0110] The above constitution prevents the dimerization andquinonization of the phenol derivative, so the resulting printed matterhas excellent light resistance and clogging resistance, as well asexcellent yellowing resistance.

[0111] A compound expressed by General Formula 1, whose weight reductionafter 1 hour at 60° C. is no more than 1%, will act effectively in thepresent invention when applied as an imparting liquid over the recordingmedium, either separately from the ink composition or by being addedthereto.

[0112] Also, in the present invention, a compound expressed by GeneralFormula 1, whose weight reduction after 1 hour at 60° C. is no more than1%, and a hydrazide compound, a tertiary amine compound, or a specificinorganic salt will act effectively in the present invention whenapplied as an imparting liquid over the recording medium, eitherseparately from the ink composition or by being added thereto.

[0113] In this case, the imparting liquid can be produced from the samecomponents as the above-mentioned ink composition, except for thecolorant.

Recording Medium

[0114] Preferred embodiments of the recording medium pertaining to thepresent invention will now be described.

[0115] An ink receiving layer comprising at least an ink absorbentpigment, an ink fixing agent, and a binder is known to allow thehigh-quality reproduction of color images, photographic images, and soon, and the ink receiving layer of the recording medium pertaining tothe embodiments of the present invention contains a compound expressedby General Formula 1, whose weight reduction after 1 hour at 60° C. isno more than 1%.

[0116] It is preferable for the compound expressed by General Formula 1to be the same as that used in the above-mentioned ink composition.

[0117] The compound expressed by General Formula 1 is preferablycontained in an amount of at least 0.01 wt % and no more than 10 wt %with respect to the total dry weight of the ink receiving layer, with atleast 0.1 wt % and no more than 5 wt % being particularly favorable.

[0118] One or more types of known white pigment can be used as the inkabsorbent pigment, examples of which include synthetic amorphous silica,colloidal silica, and other types of silica, and colloidal alumina.

[0119] Other examples of white pigments besides silica and aluminainclude light calcium carbonate, heavy calcium carbonate, magnesiumcarbonate, kaolin, talc, calcium sulfate, barium sulfate, titaniumdioxide, zinc oxide, zinc sulfide, zinc carbonate, titanium white,aluminum silicate, diatomaceous earth, calcium silicate, magnesiumsilicate, pseudo-boehmite, aluminum hydroxide, magnesium hydroxide,lithopone, zeolite, hydrated halloysite, and other such white inorganicpigments, and styrene-based plastic pigments, acrylic-based plasticpigments, polyethylene, melamine resin, urea resin, and other suchorganic pigments.

[0120] These ink absorbent pigments are preferably contained in anamount of at least 30 wt % and no more than 90 wt % with respect to thetotal dry weight of the ink receiving layer, with a range of at least 40wt % and no more than 80 wt % being particularly favorable.

[0121] A cationic compound is particularly favorable as the ink fixingagent, examples of which include low-molecular weight compounds havingprimary to tertiary amine or quaternary ammonium bases, oligomers havingthese groups, and polymers having these groups. Specific examplesinclude diallyl dimethyl ammonium chloride polymers, diallyl dimethylammonium chloride-sulfur dioxide copolymers, diallyl dimethyl ammoniumchloride-acrylamide copolymers, and other such diallyl dimethyl ammoniumsalt polymers, diallylamine hydrochloride-sulfur dioxide copolymers,diallylmethylamine hydrochloride copolymers, polyallylamines,polyethyleneimines, polyethyleneimine quaternary ammonium saltcompounds, (meth)acrylic acid alkyl ammonium salt polymers,(meth)acrylamide alkyl ammonium salt polymers, ionenes containingquaternary ammonium salts, and polyalkyleneamine dicyandiamide ammoniumsalt condensates.

[0122] These ink fixing agents are preferably contained in an amount ofat least 1 wt % and no more than 30 wt % with respect to the total dryweight of the ink receiving layer, with a range of at least 5 wt % andno more than 10 wt % being particularly favorable.

[0123] Examples of binders include oxidized starch, etherified starch,phosphoric esterified starch, and other starch derivatives,carboxylmethyl cellulose, hydroxyethyl cellulose, and other cellulosederivatives, casein, gelatin, soy protein, polyvinyl alcohol andderivatives thereof, polyvinylpyrrolidone, maleic anhydride resin,styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers,and other conjugated diene-based copolymer latexes, acrylic ester andmethacrylic ester copolymers or acrylic polymers, and other acrylicpolymer latexes, ethylene-vinyl acetate copolymers and other vinylpolymer latexes, functional group modified polymer latexes comprisingcarboxyl group and other such functional group-containing monomers ofthese various polymers, melamine resins, urea resins, and otherthermosetting resins, and other such water-based adhesive agents,polymethyl methacrylate and other acrylic ester and methacrylic esterpolymers and copolymers, polyurethane resins, unsaturated polyesterresin, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, alkydresins, and other such synthetic resin-based adhesive agents.

[0124] These binders are preferably contained in an amount of at least10 wt % and no more than 60 wt % with respect to the total dry weight ofthe ink receiving layer, with a range of at least 20 wt % and no morethan 50 wt % being particularly favorable.

[0125] If needed, the ink receiving layer may also contain various knownadditives, such as dye fixing agents (water resistance agents),fluorescent whiteners, surfactants, anti-foaming agents, pH regulators,mildewproofing agents, UV absorbents, and antioxidants.

[0126] The structure of the ink receiving layer was described above, butit is particularly favorable for the percentage of void of the inkreceiving layer to be set to between 30% and 80% by using silica oralumina as the main structural component of the ink receiving layer andadjusting the particle diameter of this silica or alumina, the amountsin which the other structural components are contained, and so forth. Ifthe percentage of void is at least 30%, the recording medium will haveparticularly good ink absorbency, and keeping this percentage to 80% orlower ensures that the ink receiving layer will have sufficientstrength.

[0127] A sheet of paper or plastic is used as the substrate, which canbe either translucent or opaque.

[0128] A conventional substrate can be used, and specific examples ofpaper include paper composed of wood-pulp or non-wood-pulp raw materialwhose main component is natural cellulose fiber, while examples ofplastic materials include polyester resins, diacetate resins, triacetateresins, acrylic resins, polycarbonate resins, polyvinyl chloride resins,polyimide resins, cellophane, and celluloid.

[0129] The recording medium of the present invention can be favorablyobtained by coating the above-mentioned substrate with a coatingsolution in which the above-mentioned structural components have beendissolved or dispersed in water or another suitable solvent, by rollcoating, spray coating, rod bar coating, air knife coating, or anotherknown coating method, and then drying this coating. A standard dryer canbe used to dry the coating, and this drying is usually performed between100 and 150° C.

[0130] The above constitution gives printed matter with excellent imagestability and light resistance, as well as excellent yellowingresistance.

[0131] The ink receiving layer of the recording medium pertaining toanother embodiment of the present invention contains a compoundexpressed by the following General Formula 1, whose weight reductionafter 1 hour at 60° C. is no more than 1%, and a hydrazide compound,tertiary amine compound, or specific inorganic salt.

[0132] The compound expressed by General Formula 1, the hydrazidecompound, the tertiary amine compound, and the inorganic salt arepreferably the same as those used for the above-mentioned inkcomposition.

[0133] The compound expressed by General Formula 1 is preferablycontained in an amount of at least 0.01 wt % and no more than 10 wt %with respect to the total dry weight of the ink receiving layer, with arange of at least 0.1 wt % and no more than 5 wt % being particularlyfavorable.

[0134] The hydrazide compound, tertiary amine compound, and inorganicsalt are preferably contained in an amount of at least 0.01 wt % and nomore than 10 wt % with respect to the total dry weight of the inkreceiving layer, with a range of at least 0.1 wt % and no more than 5 wt% being particularly favorable. Adjusting to the preferred rangemarkedly improves the yellowing resistance of the printed matter.

[0135] In the present invention, it is preferable if the compoundexpressed by General Formula 1 and the hydrazide compound, tertiaryamine compound, or inorganic salt are present in a weight ratio(former/latter) of at least 1:25 and no more than 5:1, with at least 1:5and no more than 3:1 being particularly favorable. Adjusting to thepreferred weight ratio markedly improves the yellowing resistance of theprinted matter.

[0136] The ink absorbent pigment, the ink absorbent pigment content, theink fixing agent, the ink fixing agent content, the binder, the bindercontent, the additives, and other structural features of the inkreceiving layer, and the method for manufacturing the recording mediumand the substrate are preferably the same as described above.

Recording Method

[0137] The ink jet recording method of the present invention will now bedescribed.

[0138] The ink jet recording method of the present invention allowsprinted matter with excellent light resistance and excellent yellowingresistance to be obtained by performing ink jet recording using theabove-mentioned ink composition and/or recording medium.

[0139] Furthermore, with the ink jet recording method of the presentinvention, printed matter with sufficient light resistance and excellentyellowing resistance can be obtained when the ink composition contains acolorant, water, and a compound expressed by the following GeneralFormula 1, whose weight reduction after 1 hour at 60° C. is no more than1%, and when the recording medium contains a hydrazide compound, atertiary amine compound, or a specific inorganic salt.

EXAMPLES

[0140] The present invention will now be described in more specificterms through examples, but is not limited in any way by these examples.

Examples 1 to 6 Preparation of Ink Composition

[0141] The various component combinations shown in Table 1 were stirredfor 30 minutes at normal temperature, after which each mixture waspassed through a 1 μm membrane filter to obtain various inkcompositions.

Measurement of Weight Reduction

[0142] The weight reduction in the compound expressed by General Formula1 was measured by the following method for each of the ink compositionsshown in Table 1.

[0143] Method for measuring weight reduction: Using a thermobalance is astandard and simple way of measuring weight reduction. Nitrogen or dryair was used for the atmosphere during the use of the thermobalance. Thetemperature was steadily raised from room temperature, and held for 1hour at 60° C. The heating rate is generally 1 to 10° C. per minute, andin these examples the measurements were made under a dry air environmentand at a heating rate of 5° C. per minute. TABLE 1 Ink composition No. 12 3 4 5 6 Colorant C.I. Direct Red 3 2 249 C.I. Direct Yellow 4 4 132C.I. Direct Yellow 2.5 2.5 86 Compound expressed by General Formula 1Form. 1-1 compound 0.5 7 (weight red.: −0.2%) Form. 1-2 compound 0.1 5(weight red.: −0.2%) [compound 7] 0.1 compnd. (weight red.: −1.2%)Penetrant, etc. glycerol 10 3 triethylene glycol 5 25 25 1,5-pentanediol3 5 3 5 ethylene glycol 15 20 15 Olfine E1010 1 2 2 (Nissin ChemicalIndustry Co., Ltd.) Olfine STG (Nissin 1 1 1 Chemical Industry Co.,Ltd.) diethylene glycol 10 monobutyl ether triethylene glycol 8 10 8monobutyl ether propylene glycol 5 5 monomethyl ether PreservativeProxel XL-2 0.3 0.3 0.3 0.3 0.3 0.3 (Avecia) Water bal. bal. bal. bal.bal. bal.

Light Resistance Test

[0144] Each of the above ink compositions was put into a specialcartridge for an ink jet printer (PM800C, made by Seiko Epson) andprinted onto a special ink jet recording medium (Premium Glossy PhotoPaper, made by Seiko Epson). This product was left for one day at normaltemperature and humidity away from direct light, after which the lightresistance of the printed matter was evaluated under the followingconditions.

[0145] First, optical irradiation was performed using a xenonweatherometer (Ci5000, made by Atlas), with the printed matter beingexposed with a black panel at 35° C., a relative humidity of 60%, and a340 nm UV light emission of 0.18 W/m². The irradiation conditionscomprised either 180 kJ/m² (278 hours of optical irradiation under theabove conditions) or 360 kJ/m² (556 hours of optical irradiation underthe above conditions).

[0146] After irradiation, the reflection intensity of the various colorcomponents of the printed matter was measured using a spectrophotometer(Gretag SPM, made by Gretag). The conditions here comprised a D50 lightsource, no light source filter, a white standard of absolute white, anda field angle of 2°. Intensity retention was evaluated from thefollowing criteria.

[0147] A: at least 90% of the initial value

[0148] B: at least 80% but less than 90% of the initial value

[0149] C: less than 80% of the initial value

Clogging Test

[0150] An ink cartridge filled with ink composition was installed in theabove-mentioned printer, and after it was confirmed that the inkcomposition was initially discharging normally, the power was shut offto the printer, and the ink cartridge was left installed for a period ofone to 12 months at a temperature of 40° C. and a relative humidity of20%. After the specified time had elapsed, the printer was moved to anormal temperature environment, and after the housing temperature haddropped to normal temperature, the power was turned back on and printingwas performed again, and the number of resets that had to be performeduntil the same quality was obtained as before the test was counted. Theevaluation was made according to the following criteria.

[0151] A: The same print quality as at the outset was obtained with zeroto two resets.

[0152] B: The same print quality as at the outset was obtained withthree to five resets.

[0153] C: The same print quality as at the outset was not obtained withsix or more resets.

Yellowing Resistance Test

[0154] [A special ink jet recording medium] (Premium Glossy Photo Paper,made by Seiko Epson) was printed by the same method as in the lightresistance test.

[0155] The printed matter thus obtained was then put into a clearplastic folder (CL-A420, made by Mitsubishi Pencil) and stored for aperiod of three days to one month at a temperature of 40° C. and arelative humidity of 20%. After the specified time had elapsed, theprinted matter was taken out of its plastic folder and visually checkedaccording to the following criteria for discoloration in the non-printedportions and for color change in the printed portions and thesurrounding areas.

[0156] A: No yellowing whatsoever; good.

[0157] B: Very slight yellowing noted, but not enough to pose a problemin terms of image quality.

[0158] C: The printed portions and their surroundings had yellowed.

Results of Print Evaluation Test

[0159] Table 2 gives the results of the various tests conducted usingthe above-mentioned ink compositions 1 to 6. TABLE 2 Ink composition No.1 2 3 4 5 6 Example/ Ex. Ex. Ex. Ex. CE CE Comparative Example No. 1 2 34 1 2 Light 180 kJ/m² A A A A A C resistance 360 kJ/m² A B A A B C testClogging test  1 month A A A A A A (40° C., 20% RH)  3 months A B A A BA  6 months A B B A B B 12 months A B B B B B Folder  3 days A A A A A Ayellowing  7 days A A A A B A test 14 days A A B B B A (40° C., 20% RH)28 days B A B B C A

[0160] As is clear from Table 2, in Examples 1 to 4, which featured theuse of an ink composition containing a compound expressed by GeneralFormula 1, whose weight reduction after 1 hour at 60° C. was no morethan 1 wt %, the results were all satisfactory for light resistance,clogging resistance, and folder yellowing resistance, whereasComparative Examples 1 and 2 were unsatisfactory in all of thesecategories.

Production of Recording Medium

[0161] Wood-free paper with a basis weight of 100 g/m² was used as asubstrate, and this substrate was coated with a coating solutioncomprising a mixture of water and the ink receiving layer componentslisted in Table 3 ({weight of ink receiving layer components}: {weightof water}=20:80) in an amount of 15 g/m². This was followed by dryingfor 2 minutes at 130° C. using a dryer, which produced recording media Ato D. TABLE 3 Recording medium A B C D Compound of Form. 1-1 compound0.5 General (weight reduction: −0.2%) Formula 1 Form. 1-2 compound 4(weight reduction: −0.2%) [compound 7] compound 0.5 (weight reduction:−1.2%) Ink absorbent Silica Gel P78D (made by 60 pigment MizusawaChemical Industries) Ink fixing diallyl methyl ammonium  9 agentchloride-sulfur dioxide copolymer, PAS-A (made by Nitto Boseki) Binderpolyvinyl alcohol, CM318 balance (degree of polymerization: 1800; madeby Kuraray)

Results of Print Evaluation Test

[0162] The above-mentioned ink compositions and recording media werevariously combined as shown in Table 4, printing was performed, and alight resistance test and yellowing resistance test were conducted bythe same methods as above. The results of these tests are given in Table4. TABLE 4 Ink composition No. 6 Recording medium A B C D Example/ Ex.Ex. C.E. C.E. Comparative Example No. 5 6 3 4 Light 180 kJ/m² A A A Cresistance 360 kJ/m² B A B C test Folder  3 days A A A A yellowing  7days A A B A test 14 days A A B A 28 days A B C A

[0163] As is clear from Table 4, in Examples 5 and 6, in which eitherthe ink composition or the recording medium contained a compoundexpressed by General Formula 1, whose weight reduction after 1 hour at60° C. was no more than 1 wt %, the results were all satisfactory forlight resistance, clogging resistance, and folder yellowing resistance,whereas Comparative Examples 3 and 4 were unsatisfactory in all of thesecategories.

Examples 7 to 33 Preparation of Ink Composition

[0164] The various components shown in Tables 5 and 6 were stirred for30 minutes at normal temperature, after which the system was passedthrough a 1 μm membrane filter to obtain various ink compositions.

Measurement of Weight Reduction

[0165] The weight reduction in the compound expressed by General Formula1 was measured by the following method for each of the ink compositionsshown in Tables 5 and 6.

[0166] Method for measuring weight reduction: Using a thermobalance is astandard and simple way of measuring weight reduction. Nitrogen or dryair was used for the atmosphere during the use of the thermobalance. Thetemperature was steadily raised from room temperature, and held for 1hour at 60° C. The heating rate is generally 1 to 10° C. per minute, andin these examples the measurements were made under a dry air environmentand at a heating rate of 5° C. per minute. TABLE 5 Ink composition No. 12 3 4 5 6 7 8 9 10 11 12 Colorant C.I. Direct Red 249 2 3 3 C.I. DirectYellow 4 3 4 4 132 C.I. Direct Yellow 2.5 2.5 2.5 86 Compound expressedby Form. 1-1 compound 0.5 0.1 0.5 0.1 0.5 0.1 General Formula 1 (weightred.: −0.2%) Form. 1-2 compound 0.4 8 4 0.4 (weight red.: −0.2%)[compound 10] compnd. (weight red.: −1.2%) Additiv Hydrazide compoundsForm. 3-3 compound 2 10 Form. 3-4 compound 2 Form. 3-11 compound 0.1 0.1Form. 3-13 compound 4 Tertiary amine 1,4-diazabicyclo[2.2.2] 2 1 0.1compounds octane (DABCO) hexamethylene tetramine 1 (HMTA) In potassiumsulfite or (K₂SO₃) lithium thiosulfate (Li₂S₂O₃) potassium hypophosphite(KPH₂O₂) sodium phosphite (Na₂PHO₃) Penetrant, etc. glycerol 13 2 8 1313 12 triethylene glycol 30 10 2 30 26 1,5-pentanediol 4 4 5 ethyleneglycol 14 14 13 Olfine E1010 (Nissin 1 2 1 1 2 1 1 2 Chemical IndustryCo., Ltd.) Olfine STG (Nissin 1 0.5 1 1 Chemical Industry Co., Ltd.)diethylene glycol 10 9 10 10 9 monobutyl ether triethylene glycol 8 10 810 monobutyl ether propylene glycol 5 5 5 mononothyl ether PreservativeProxel XL-2 (Avecia) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3Water B B B B B B B B B B B B

[0167] TABLE 6 Ink composition No. 13 14 15 16 17 18 19 20 21 22 23 24Colorant C.I. Direct Red 249 2 3 2 3 C.I. Direct Yellow 3 4 3 4 4 132C.I. Direct Yellow 2.5 2.5 2.5 86 Compound expressed by Form. 1-1compound 0.5 0.1 0.5 General Formula 1 (weight red.: −0.2%) Form. 1-2compound 8 4 0.4 8 4 (weight red.: −0.2%) [compound 10] compnd. 0.1 0.1(weight red.: −1.2%) Additiv Hydrazide compounds Form. 3-3 compound 2 1Form. 3-4 compound Form. 3-11 compound Form. 3-13 compound Tertiaryamine 1,4-diazabicyclo[2.2. 10 0.1 compounds 2]octane (DABCO)hexamethylene 4 tetramine (HMTA) Inorganic potassium sulfite 2 (K₂SO₃)lithium thiosulfate 2 0.1 0.1 1 (Li₂S₂O₃) potassium 4 hypophosphite(KPH₂O₂) sodium phosphite 10 (Na₂PHO₃) Penetrant, etc. glycerol 5 2 12 52 5 12 triethylene glycol 10 26 10 25 30 1,5-pentanediol 5 6 3 ethyleneglycol 8 13 13 7 13 Olfine E1010 (Nissin 0.5 2 1 0.5 2 2 2 2 1 Chemical)Olfine STG (Nissin 2 2 1.5 Chemical) diethylene glycol 10 10 9 10monobutyl ether triethylene glycol 10 10 10 8 8 monobutyl etherpropylene glycol 5 6 6 mononothyl ether Preservative Proxel XL-2(Avecia) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Water B B B B BB B B B B B B

Light Resistance Test

[0168] Each of the above ink compositions was put into a specialcartridge for an ink jet printer (PM800C, made by Seiko Epson) andprinted onto a special ink jet recording medium (PM photographic paper,made by Seiko Epson). This product was left for one day at normaltemperature and humidity away from direct light, after which the lightresistance of the printed matter was evaluated under the followingconditions.

[0169] First, optical irradiation was performed using a xenonweatherometer (Ci5000, made by Atlas), with the printed matter beingexposed with a black panel at 35° C., a relative humidity of 60%, and a340 nm UV light emission of 0.18 W/m². The irradiation conditionscomprised either 180 kJ/m² (278 hours of optical irradiation under theabove conditions) or 360 kJ/m² (556 hours of optical irradiation underthe above conditions).

[0170] After irradiation, the reflection intensity of the various colorcomponents of the printed matter was measured using a spectrophotometer(Gretag SPM, made by Gretag). The conditions here comprised a D50 lightsource, no light source filter, a white standard of absolute white, anda field angle of 2°. Intensity retention was evaluated from thefollowing criteria.

[0171] A: at least 90% of the initial value

[0172] B: at least 80% but less than 90% of the initial value

[0173] C: less than 80% of the initial value

Clogging Test

[0174] An ink cartridge filled with ink composition was installed in theabove-mentioned printer, and after it was confirmed that the inkcomposition was initially discharging normally, the power was shut offto the printer, and the ink cartridge was left installed for a period ofone to 12 months at a temperature of 40° C. and a relative humidity of20%. After the specified time had elapsed, the printer was moved to anormal temperature environment, and after the housing temperature haddropped to normal temperature, the power was turned back on and printingwas performed again, and the number of resets that had to be performeduntil the same quality was obtained as before the test was counted. Theevaluation was made according to the following criteria.

[0175] A: The same print quality as at the outset was obtained with zeroto two resets.

[0176] B: The same print quality as at the outset was obtained withthree to five resets.

[0177] C: The same print quality as at the outset was not obtained withsix or more resets.

Yellowing Resistance Test

[0178] A special ink jet recording medium (Premium Glossy Photo Paper,made by Seiko Epson) was printed by the same method as in the lightresistance test.

[0179] The printed matter thus obtained was then put into a clearplastic file (CL-A420, made by Mitsubishi Pencil) and stored for aperiod of three days to one month at a temperature of 60° C. and arelative humidity of 20%. After the specified time had elapsed, theprinted matter was taken out of its plastic folder and visually checkedaccording to the following criteria for color change in the non-printedportions and for discoloration in the printed portions and thesurrounding areas.

[0180] A: No yellowing whatsoever; good.

[0181] B: Very slight yellowing noted, but not enough to pose a problemin terms of image quality.

[0182] C: The printed portions and their surroundings had yellowed.

Results of Print Evaluation Test

[0183] Tables 7 and 8 give the results of the various tests conductedusing the above-mentioned ink compositions 1 to 24. TABLE 7 Inkcomposition No. 1 2 3 4 5 6 7 8 9 10 11 12 Example/Comparative Ex Ex ExEx Ex CE CE CE CE Ex Ex Ex Example No. 7 8 9 10 11 5 6 7 8 12 13 14Ratio of compound of 1:4 1:20 4:1 2:1 1:2.5 — — — — 1:4 1:20 4:1 GeneralFormula 1 and additive Light 180 kJ/m² A A A A A A A C C A A Aresistance 360 kJ/m² A B B A A A B C C A B B test Clogging one month A AA A A A A A A A A A resistance three A B A A A A B A A A B A test (40°C., months 20% RH) six A B B B A A B A B A B B months 12 months A B B BB A B A B A B B Folder three A A B A A A A A A A A B yellowing days test(60° C., seven A A B B A B B A A B B B 20% RH) days 14 days B A B B B CB A A B B B 28 days B B B B B C C A A B B B

[0184] TABLE 8 Ink composition No. 13 14 15 16 17 18 19 20 21 22 23 24Example/Comparative Ex Ex CE Ex Ex Ex Ex Ex CE CE CE Ex Example No. 1516 9 17 18 19 20 21 10 11 12 22 Ratio of compound of 2:1 1:2.5 — 1:41:20 4:1 2:1 1:2.5 — — 1:20 1:4 General Formula 1 and additive Lightresist- 180 kJ/m² A A C A A A A A C A A A ance test 360 kJ/m² A A C A BB A A C B B A Clogging one month A A A A A A A A A A A A resistancethree A A A A A A A A A B B A test (40° C., months 20% RH) six months BA B A A B B A B B B A 12 months B B B A B B B B B B B A Folder threedays B A A A A B A A A B A A yellowing seven days B B A A A B B A A C BA test (60° C., 14 days B B A B B B B B A C C B 20% PH) 28 days B B A BB B B B A C C B

[0185] As is clear from Tables 7 and 8, light resistance, cloggingresistance, and folder yellowing resistance could not all be satisfiedwith Comparative Examples 5 to 12, whereas the results were satisfactoryfor all of these with Examples 7 to 22.

Production of Recording Medium

[0186] Wood-free paper with a basis weight of 100 g/m² was used as asubstrate, and this substrate was coated with a coating solutioncomprising a mixture of water and the ink receiving layer componentslisted in Table 9 ({weight of ink receiving layer components}: [weightof water}=20:80) in an amount of 15 g/m². This was followed bydrying^([8]) for 2 minutes at 130° C. using a dryer, which producedrecording media A to P. TABLE 9 Recording medium A B C D E F G H I J K LM N O P Compound of General Formula 1 Form. 1-1 compound 0.5 4 0.5 4 0.54 (weight reduction: −0.2%) Form. 1-2 compound 0.5 4 (weight reduction:−0.2%) [compound 7] compound 0.5 (weight reduction: −1.2%) HydrazineCompounds Form. 3-4 compound 0.5 4 1 4 4 Tertiary Amine Compounds1,4-diazabicyclo[2.2.2]octane 0.5 0.5 (DABCO) hexamethylene tetramine(HMTA) 4 4 Inorganic Salts sodium phosphite (Na₂PHO₃) 0.5 0.5 4potassium hypophosphite (KPH₂O₂) 4 4 Ink absorbent Silica Gel P78D(trade name of Mizusawa Chemical 60 pigment Industries) Ink fixing agentdiallyl methyl ammonium chloride-sulfur dioxide 9 copolymer, PAS-A(trade name of Nitto Boseki) Binder polyvinyl alcohol, CM318 (degree ofpolymer- balance ization: 1800; trade name of Kuraray)

Results of Print Evaluation Test

[0187] The above-mentioned ink compositions and recording media werevariously combined as shown in Tables 10 and 11, printing was performed,and a light resistance test and yellowing resistance test were conductedby the same methods as above. The results of these tests are given inTables 10 and 11. TABLE 10 Ink composition No. 1 6 8 Recording medium AC E F H E B D E N O P Example/Comparative Ex Ex Ex Ex Ex CE Ex CE CE CECE Ex Example No. 23 24 25 26 27 13 28 14 15 16 17 29 Light 180 A A A AA A A C C A A A resistance kJ/m² test 360 B B B B B B A C C B B A kJ/m²Folder  3 days A A A B A B A A A A B A yellow-  7 days A A A B B B A A AB C B ing 14 days A A A B B C B A A C C B resistance 28 days B A A B B CB A A C C B test (60° C., 20% RH)

[0188] TABLE 1 Ink composition No. 9 10 21 Recording medium G I E J L EK M E Example/Comparative Ex CE CE Ex Ex CE Ex CE CE Example No. 30 1819 31 32 20 33 21 22 Light resist- 180 A C C A A A A C C ance test kJ/m²360 A C C B B B A C C kJ/m² Folder  3 days A A A A A B A A A yellow-  7days B A A B B B B A A ing 14 days B A A B B C B A A resistance 28 daysB A A B B C B A A test (60° C., 20% RH)

[0189] As is clear from Tables 10 and 11, light resistance, cloggingresistance, and folder yellowing resistance could not all be satisfiedwith Comparative Examples 13 to 22, whereas the results weresatisfactory for all of these with Examples 23 to 33.

[0190] With the ink composition and recording medium of the presentinvention, and with the ink jet recording method of the presentinvention, it is possible to obtain a high-quality image with excellentlight resistance of the printed matter, with no clogging, and withexcellent yellowing resistance of the printed matter.

[0191] Furthermore, the printed matter of the present invention hasexcellent light resistance of the recorded images, as well as excellentyellowing resistance.

What is claimed is:
 1. An ink composition comprising a colorant, water,and a compound expressed by the following General Formula 1,

(in General Formula 1, X is a hydrogen, oxy radical, hydroxyl group,alkyl group, alkenyl group, alkynyl group, aryl group, acyl group,sulfonyl group, sulfinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are each a hydrogen or alkyl group; Z is agroup of nonmetal atoms necessary to complete a five- to seven-memberring; and any two groups out of R¹ to R⁴ and Z may bond together to forma five- to seven-member ring), wherein the weight reduction in thecompound expressed by said General Formula 1 after 1 hour at 60° C. isno more than 1%.
 2. The ink composition according to claim 1, whereinthe compound expressed by General Formula 1 is a compound expressed bythe following general formula having a water-soluble group W:

(where W is a —SO₂NH₂ group, —NHCOCH₃ group, —CONH₂ group, —C═NH(NH₂)group, —NHC═NH(NH₂) group, —SO₃H group, sulfuric ester group, —P(O) (OH)(OR), —P(O) (OR)₂, carbamoyl group or salt thereof, salt of a carboxylgroup, salt of an amino group, salt of a phenolic hydroxyl group,polyethylene glycol ether group, salt of —C═NH(NH₂), or salt of—NHC═NH(NH₂) (R is an alkyl group or aryl group); X is a hydrogen, oxyradical, hydroxyl group, alkyl group, alkenyl group, alkynyl group, arylgroup, acyl group, sulfonyl group, sulfinyl group, alkoxy group, aryloxygroup, or acyloxy group; R¹, R², R³, and R⁴ are each a hydrogen or alkylgroup; Z is a group of nonmetal atoms necessary to complete a five-toseven-member ring; and any two groups out of R¹ to R⁴ and Z may bondtogether to form a five- to seven-member ring).
 3. The ink compositionaccording to claim 1, wherein, in the compound expressed by GeneralFormula 1, Z is a group of nonmetal atoms necessary to complete asix-member ring.
 4. The ink composition according to claim 1, wherein,in the compound expressed by General Formula 1, X is an oxy radical. 5.The ink composition according to claim 1, wherein the compound expressedby General Formula 1 is contained in the ink composition in an amount ofat least 0.05 wt % and no more than 10 wt %.
 6. The ink compositionaccording to claim 1, further comprising a penetrant and/or a humectant.7. A recording medium comprising an ink receiving layer provided on asubstrate, wherein the ink receiving layer contains a compound expressedby the following General Formula 1, whose weight reduction after 1 hourat 60° C is no more than 1%:

(in General Formula 1, X is a hydrogen, oxy radical, hydroxyl group,alkyl group, alkenyl group, alkynyl group, aryl group, acyl group,sulfonyl group, sulfinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are each a hydrogen or alkyl group; Z is agroup of nonmetal atoms necessary to complete a five- to seven-memberring; and any two groups out of R¹ to R⁴ and Z may bond together to forma five- to seven-member ring).
 8. The recording medium according toclaim 7, wherein the compound expressed by General Formula 1 iscontained in an amount of at least 0.01 wt % and no more than 10 wt %with respect to the total amount of the ink receiving layer.
 9. An inkjet recording method in which droplets of an ink composition aredischarged, and said droplets are made to adhere to a recording medium,wherein the ink composition according to claim 1 is used as the inkcomposition.
 10. An ink jet recording method in which droplets of an inkcomposition are discharged, and said droplets are made to adhere to arecording medium, wherein the recording medium according to claim 7 isused as the recording medium.
 11. An ink jet recording method in whichdroplets of an ink composition are discharged, and said droplets aremade to adhere to a recording medium, wherein the ink compositionaccording to claim 1 is used as the ink composition, and the recordingmedium according to claim 7 is used as the recording medium.
 12. Printedmatter, recorded by the ink jet recording method according to claim 9.13. The ink composition according to claim 1, further containing atleast one type of compound A selected as desired from among the threegroups numbered I to III below. Group I: hydrazide compounds Group II:tertiary amine compounds Group III: inorganic salts expressed by MS₂O₄,MSO₃, MS₂O₃, MPH₂O₂, and MPHO₃ (where M is an alkali metal or alkalineearth metal)
 14. The ink composition according to claim 13, wherein thecompound expressed by General Formula 1 is a compound expressed by thefollowing general formula having a water-soluble group W:

(where W is a —SO₂NH₂ group, —NHCOCH₃ group, —CONH₂ group, —C═NH(NH₂)group, —NHC═NH(NH₂) group, —SO₃H group, sulfuric ester group, —P(O) (OH)(OR), —P(O) (OR)₂, carbamoyl group or salt thereof, salt of a carboxylgroup, salt of an amino group, salt of a phenolic hydroxyl group,polyethylene glycol ether group, salt of —C═NH(NH₂), or salt of—NHC═NH(NH₂) (R is an alkyl group or aryl group); X is a hydrogen, oxyradical, hydroxyl group, alkyl group, alkenyl group, alkynyl group, arylgroup, acyl group, sulfonyl group, sulfinyl group, alkoxy group, aryloxygroup, or acyloxy group; R¹, R², R³, and R⁴ are each a hydrogen or alkylgroup; Z is a group of nonmetal atoms necessary to complete a five-toseven-member ring; and any two groups out of R¹ to R⁴ and Z may bondtogether to form a.five- to seven-member ring).
 15. The ink compositionaccording to claim 13, wherein, in the compound expressed by GeneralFormula 1, Z is a group of nonmetal atoms necessary to complete asix-member ring.
 16. The ink composition according to claim 13, wherein,in the compound expressed by General Formula 1, X is an oxy radical. 17.The ink composition according to claim 13, wherein compound A iscontained in the ink composition in an amount of at least 0.01 wt % andno more than 10 wt %.
 18. The ink composition according to claim 13,wherein the compound expressed by General Formula 1 is contained in theink composition in an amount of at least 0.05 wt % and no more than 10wt %.
 19. The ink composition according to claim 13, wherein thecompound expressed by General Formula 1 and compound A are present in aweight ratio (former/latter) of at least 1:25 and no more than 5:1. 20.The ink composition according to claim 13, wherein compound A representsgroup I.
 21. The ink composition according to claim 13, wherein compoundA represents group II.
 22. The ink composition according to claim 13,wherein compound A represents group III.
 23. The ink compositionaccording to claim 13, wherein the hydrazide compound is a compoundexpressed by the general formula R⁵CXNHNR⁶R⁷ (where R⁵ is an alkyl groupor aryl group; R⁶ and R⁷ are a hydrogen, alkyl group, or aryl group; andX is S or O), or the general formula R⁵SO₂NHNR⁶R⁷ (where R⁵ is an alkylgroup or aryl group; and R⁶ and R⁷ are a hydrogen, alkyl group, or arylgroup).
 24. The ink composition according to claim 13, wherein thehydrazide compound is a compound expressed by the general formulaR⁵NHCXNHNR⁶R⁷ (where R⁵ is an alkyl group or aryl group; R⁶ and R⁷ are ahydrogen, alkyl group, or aryl group; and X is S or O).
 25. The inkcomposition according to claim 13, wherein the hydrazide compound hastwo or more hydrazide structures per molecule.
 26. The ink compositionaccording to claim 13, wherein the tertiary amine compound is a compoundexpressed by the general formula R⁵R⁶R⁷N (where R⁵, R⁶, and R⁷ are eacha substitutable alkyl group, aryl group, or aralkyl group).
 27. The inkcomposition according to claim 13, wherein the tertiary amine compoundis a substitutable cyclic tertiary amine.
 28. The ink compositionaccording to claim 13, wherein the tertiary amine compound is1,4-diazabicyclo[2.2.2]octane and/or hexamethylenetetramine.
 29. The inkcomposition according to claim 13, wherein the inorganic salt is apotassium salt or sodium salt.
 30. The ink composition according toclaim 13, further comprising a penetrant and/or a humectant.
 31. Therecording medium according to claim 7, further containing in the inkreceiving layer at least one type of compound A selected as desired fromamong the three groups numbered I to III below. Group I: hydrazidecompounds Group II: tertiary amine compounds Group III: inorganic saltsexpressed by MS₂O₄, MSO₃, MS₂O₃, MPH₂O₂, and MPHO₃ (where M is an alkalimetal or alkaline earth metal)
 32. The recording medium according toclaim 31, wherein compound A is contained in an amount of at least 0.01wt % and no more than 10 wt % with respect to the total amount of theink receiving layer.
 33. The recording medium according to claim 31,wherein the compound expressed by General Formula 1 is contained in anamount of at least 0.01 wt % and no more than 10 wt % with respect tothe total amount of the ink receiving layer.
 34. The ink compositionaccording to claim 31, wherein the compound expressed by General Formula1 and compound A are present in a weight ratio (former/latter) of atleast 1:25 and no more than 5:1.
 35. An ink jet recording method inwhich droplets of an ink composition are discharged, and said dropletsare made to adhere to a recording medium, wherein the ink compositionaccording to claim 13 is used as the ink composition.
 36. An ink jetrecording method in which droplets of an ink composition are discharged,and said droplets are made to adhere to a recording medium, wherein therecording medium according to claim 31 is used as the recording medium.37. An ink jet recording method in which droplets of an ink compositionare discharged, and said droplets are made to adhere to a recordingmedium, wherein the ink composition according to claim 13 is used as theink composition, and the recording medium according to claim 31 is usedas the recording medium.
 38. An ink jet recording method in whichdroplets of an ink composition are discharged, and said droplets aremade to adhere to a recording medium, wherein the ink compositionaccording to claim 13 is used as the ink composition, and a recordingmedium comprising an ink receiving layer provided on a substrate, andcontaining at least one type of compound A selected as desired fromamong the three groups numbered I to III below, is used as the recordingmedium. Group I: hydrazide compounds Group II: tertiary amine compoundsGroup III: inorganic salts expressed by MS₂O₄, MSO₃, MS₂O₃, MPH₂O₂, andMPHO₃ (where M is an alkali metal or alkaline earth metal)
 39. An inkjet recording method in which droplets of an ink composition aredischarged, and said droplets are made to adhere to a recording medium,wherein an ink composition comprising a colorant, water, and at leastone type of compound A selected as desired from among the three groupsnumbered I to III below is used as the ink composition, and therecording medium according to claim 31 is used as the recording medium.Group I: hydrazide compounds Group II: tertiary amine compounds GroupIII: inorganic salts expressed by MS₂O₄, MSO₃, MS₂O₃, MPH₂O₂, and MPHO₃(where M is an alkali metal or alkaline earth metal)
 40. An ink jetrecording method in which droplets of an ink composition are discharged,and said droplets are made to adhere to a recording medium, wherein theink composition comprises a colorant, water, and a compound expressed bythe following General Formula 1, whose weight reduction after 1 hour at60° C. is no more than 1%, and the recording medium comprises an inkreceiving layer provided on a substrate, and contains at least one typeof compound A selected as desired from among the three groups numbered Ito III below, is used as the recording medium Group I: hydrazidecompounds Group II: tertiary amine compounds Group III: inorganic saltsexpressed by MS₂O₄, MSO₃, MS₂O₃₁ MPH₂O₂, and MPHO₃ (where M is an alkalimetal or alkaline earth metal)

(in General Formula 1, X is a hydrogen, oxy radical, hydroxyl group,alkyl group, alkenyl group, alkynyl group, aryl group, acyl group,sulfonyl group, sulfinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are each a hydrogen or alkyl group; Z is agroup of nonmetal atoms necessary to complete a five- to seven-memberring; and any two groups out of R¹ to R⁴ and Z may bond together to forma five- to seven-member ring).
 41. An ink jet recording method in whichdroplets of an ink composition are discharged, and said droplets aremade to adhere to a recording medium, wherein an ink compositioncomprising a colorant, water, and a compound A expressed by thefollowing General Formula 1, whose weight reduction when left for 1 hourat 60° C. is no more than 1 wt %, is used as the ink composition, andthe recording medium according to claim 31 is used as the recordingmedium:

(in General Formula 1, X is a hydrogen, oxy radical, hydroxyl group,alkyl group, alkenyl group, alkynyl group, aryl group, acyl group,sulfonyl group, sulfinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are each a hydrogen or alkyl group; Z is agroup of nonmetal atoms necessary to complete a five- to seven-memberring; and any two groups out of R¹ to R⁴ and Z may bond together to forma five- to seven-member ring).
 42. The ink jet recording methodaccording to claim 40, wherein the compound expressed by General Formula1 is contained in the ink composition in an amount of at least 0.05 wt %and no more than 10 wt %.
 43. The ink jet recording method according toclaim 39, wherein compound A is contained in the ink composition in anamount of at least 0.01 wt % and no more than 10 wt %.
 44. The ink jetrecording method according to claim 38, wherein compound A is containedin the recording medium in an amount of at least 0.01 wt % and no morethan 10 wt %.
 45. Printed matter, recorded by the ink jet recordingmethod according to claim 35.